This is neat, and there's a lot of interesting comments and pointers elsewhere in these comment threads.

What I've been doing (for the last 25 years or so) is simple. I always keep a window open, visible in all virtual desktops, on the bottom right of my screen, with: vi ~/notes/notes

For somewhat less than the last 25 years, ~/notes is an encrypted git repo. I have a cron that, minutely, adds, commits, pulls and pushes to a couple of my servers on the Internet.

I generally have one of these for each company I work for, and another one that I've used for all things personal.